Due to an increasing number of wireless devices and a growing demand for wireless services, wireless communication systems continue to expand. To meet the growing demand, wireless providers have deployed a greater number of wireless transmitters. As an alternative, however, wireless providers have also utilized relay-based systems.
In a relay-based system, one node of a wireless system may communicate with another node in the wireless system using one or more intermediary nodes, called relay nodes. In some systems, the relay node may be referred to as a relay station, and the combination of nodes and connections between an originating node and a destination node may be referred to as a transmission path. Relay-based systems may be found in any type of wireless network.
An example of a relay-based system is a multi-hop relay (MR) network. FIG. 1 is a diagram of an exemplary prior art MR network 100 based on the Institute of Electrical and Electronics Engineers (IEEE) 802.16 family of standards.
As shown in FIG. 1, MR network 100 may include one or more transmitters, e.g., base station (BS) 110, one or more relay stations (RS) 120, including RSs 120a, 120b, and 120c, and one or more subscriber stations (SS) 130, including SSs 130w, 130x, 130y, and 130z. 
In MR network 100, communication between a transmitter station (e.g., BS 110) and subscriber stations (e.g., SS 130w, SS 130x, SS 130y, SS 130z, etc.) may be achieved using one or more relay stations (e.g., RS 120a, RS 120b, RS 120c, etc.). For example, in MR network 100, RS 120a may receive data from BS 110 and send the data to another relay station (e.g., RS 120b). Alternatively, RS 120a may receive data from a subordinate relay station (e.g., RS 120b), and send it to BS 110. As another example, RS 120c may receive data from RS 120b and send the data to a supported subscriber station (e.g., SS 130w). Alternatively, RS 120c may receive data from a subscriber station (e.g., SS 130w), and send it to a dominant relay station (e.g., RS 120b).
Some embodiments, such as MR network 100, may use a scheduling algorithm by which subscriber stations (e.g., SS 130w, SS 130x, SS 130y, SS 130z, etc.) may compete only once for initial entry into the network (i.e., the communication network provided by serving BS 110 to subscriber stations within range). Once initial entry into the network is accomplished, access slots may be allocated by BS 110. In other embodiments, access slots may be dynamically allocated in each frame interval. In either case, the access slots may be enlarged or contracted, but the access slot remains assigned to a specific subscriber station, thereby precluding the use of the access slot by other subscriber stations.
FIG. 2 illustrates an exemplary Media Access Control (MAC) frame format based on the IEEE 802.16 family of standards using Orthogonal Frequency-Division Multiple Access (OFDMA). As shown in FIG. 2, transmission time may be divided into variable length sub-frames: an uplink (UL) sub-frame and a downlink (DL) sub-frame. Although not shown in detail, the UL sub-frame may include ranging channels, a channel quality information channel (CQICH), and UL data bursts containing data.
The DL sub-frame may include a preamble, a Frame Control Header (FCH), a DL-MAP, a UL-MAP, and a DL data burst area. The preamble may be used to provide a reference for synchronization. For example, the preamble may be used to adjust a timing offset, a frequency offset, and power. The FCH may contain frame control information for each connection including, for example, decode information for SSs 130.
DL-MAP and UL-MAP messages may be used to allocate channel access for downlink and uplink communication, respectively. That is, the DL-MAP message may provide a directory of access slot locations within the current downlink sub-frame, and the UL-MAP message may provide a directory of access slot locations within the current uplink sub-frame. In the DL-MAP message, this directory may take the form of one or more DL-MAP Information Elements (MAP IEs). Each MAP IE in the DL-MAP message may contain parameters for a single connection (i.e., the connection with a single SS 130). These parameters may be used to identify where, in the current sub-frame, a data burst may be located, the length of the data burst, the identity of the intended recipient of the data burst, and one or more transmission parameters.
For example, each MAP IE may contain a Connection ID (CID), identifying the destination device (e.g., SS 130w, SS 130x, SS 130y, SS 130z, etc.) for which a data burst is intended, a Downlink Interval Usage Code (DIUC), representing a downlink interval usage code by which downlink transmission is defined, an OFDMA Symbol Offset, indicating the offset of the OFDMA symbol in which a data burst starts, a sub-channel offset, indicating the lowest-index OFDMA sub-channel for carrying the burst, etc. Other parameters may also be included in the MAP IE including, for example, a boosting parameter, a parameter indicating a number of OFDMA symbols, a parameter indicating a number of sub-channels, etc. As used herein, prior art MAC headers and MAP IEs may be referred to as connection-switched control data.
DL-MAP and UL-MAP messages may each be followed by a data burst area. The data burst area may include one or more data bursts. Each data burst in the data burst area may be modulated and coded according to the control type of a corresponding connection-switched control data. For example, referring to FIG. 3, MAP IE “w” may provide control information for data burst “w,” MAP IE “x” may provide control information for data burst “x,” MAP IE “y” may provide control information for data burst “y,” and MAP IE “z” may provide control information for data burst “z.”
Referring again to FIG. 1, BS 110 may receive data bursts for SS 130w, SS 130x, SS 130y, and SS 130z, each of which are subscriber devices to RS 120c. BS 110 may generate connection-switched control data for each SS 130, inserting the connection-switched control data into a DL MAP IE slot of a frame. BS 110 may insert the associated data burst for each SS 130 into a data burst area corresponding to each connection-switched control data. BS 110 may transmit the frame to the first node along the transmission path, i.e., RS 120a. RS 120a may receive the data, and process each connection-switched control data to determine if any data is intended for a subscriber device of RS 120a. If none of the data is intended for a subscriber device of RS 120a, RS 120a may forward the data to the next RS 120 along the transmission path. In this example, none of the data is intended for a subscriber device of RS 120a, and RS 120a may transmit the data to RS 120b. 
Similarly, RS 120b may receive the data, and process each control data to determine if any data is intended for a subscriber device of RS 120b. If none of the data is intended for a subscriber device of RS 120b, RS 120b may also forward the data to the next RS 120 along the transmission path, i.e., RS 120c. RS 120c may receive the data, and process each control data to determine if any data is intended for a subscriber device of RS 120c. In this example, SS 130w, SS 130x, SS 130y, and SS 130z are subscriber devices of RS 120c, and RS 120c may process the connection-switched control data, forwarding the appropriate data to each SS 130 according to the transmission parameters stored in the MAP IE.
In MR network 100, each RS 120 along the transmission path may process every connection-switched control data (e.g., MAC header and MAP IEs) in the frame until the individual control data, and their associated data, reach their destinations. Thus, for example, each of the connection-switched control data of FIG. 1 may be processed three times before they reach their destination. This may cause significant usage of system resources and corresponding transmission latency.